Allocated-limit arithmetic
Crusher-Rotor Residual Unbalance
Use a traceable residual-unbalance limit that has already been selected for the actual rotor behaviour and allocated to the stated tolerance/correction plane. Optional inputs convert that limit without inventing a crusher balance grade.
Allocated-limit conversions
For two elements at the same radius and opposite angular positions, their net unbalance magnitude is |m1−m2|re. The displayed pair value is therefore a conservative ceiling only when the entire stated U budget is assigned to that one pair and other unbalance vectors are zero. It is not a general per-element tolerance and is never divided by the number of hammers or blow bars.
ISO 21940-11:2016 with Amd 1:2022 covers procedures and tolerances for rotors with rigid behaviour, including required correction planes, allocation to tolerance planes and balancing-process errors. ISO 21940-12:2016 addresses flexible behaviour and explicitly is not an acceptance specification for every rotor.
The old crusher-specific G6.3/G16/G40 table was not supported by an identified current standard clause or manufacturer specification and has been removed. Select and allocate U using the licensed applicable document and the actual rotor design; this page performs only transparent conversions.
ISO 20816-3:2022 provides in-situ vibration-evaluation guidance for listed industrial machine types and warns that machine-specific features may make numerical guidelines inappropriate. This page does not apply generic crusher bands such as 10, 18 or 28 mm/s. The current ISO page also shows ISO 20816-3 is being revised.
No bearing-life or safety claim: adding unbalance force directly to bearing dynamic rating C is not an ISO 281 life calculation. Bearing life requires the actual equivalent dynamic load, load direction/distribution, bearing data, duty cycle and other factors. Field correction, welding and trial runs require an OEM-approved method, guarding, risk assessment and qualified personnel.
